the tank is 240 litre's and there 9 zebra danios, 6 mollies, 4 guppies, 2 dwarf gouramis, 2 clown loaches and 1 clown pleco.
the tank has been set up for 9 week's and i took some of my water to my lfs a couple weeks ago and they said it was ok.
the zebra danio has just been doing it today i just noticed it before, ive also noticed other danios and some mollies have redness in gills to.